1. Field of the Invention
The present invention relates to a substrate processing apparatus, and more particularly, to a semiconductor manufacturing apparatus for processing and manufacturing a semiconductor wafer.
2. Description of the Related Art
Prior art for placing and taking out a wafer on and from a susceptor in a reaction chamber having the susceptor therein will be described below.
FIG. 10 is a schematic sectional view of a reaction chamber 900 described in Japanese Patent Application Laid-open No. H6-318630. A wafer 902 is processed in a reaction chamber 901 in a state where the wafer 902 is placed on a susceptor 903. The wafer 902 rotates together with the susceptor 903 and a susceptor supporting cradle 905.
Next, a taking out operation of the wafer 902 will be explained. A hollow driving shaft 904 moves downward in a state where the susceptor 903 stops rotating, and with this downward motion, the susceptor supporting cradle 905, the susceptor 903, the wafer 902 and wafer supporting pins 906 also move downward. Among their downward movements, the downward movement of the wafer supporting pins 906 is stopped by an arm 907 during its downward motion.
Since the wafer supporting pins 906 are located in through holes 913 in the susceptor 903, the hollow driving shaft 904 further moves downward, and the susceptor supporting cradle 905 and the susceptor 903 keep moving downward even after the downward movement of the wafer supporting pins 906 is stopped.
As a result, the wafer 902 is separated from the susceptor 903 by the wafer supporting pins 906. Then, a wafer transfer arm 911 is inserted between the wafers 902 and the susceptor 903 from an access port 910. Next, a wafer supporting cradle 909 comprising the arm 907 and a hollow shaft 908 moves downward together with the susceptor supporting cradle 905, and the wafer 902 is placed on the wafer transfer arm 911.
By pulling the wafer transfer arm 911 from the reaction chamber 901, the wafer 902 can be taken out from the reaction chamber 901. Since the wafer 902 can be transferred into the reaction chamber 901 by reversing the taking out procedure, its explanation will be omitted here.
According to this prior art, the wafer supporting pins 906 are brought into contact with the arm 907 by moving the susceptor supporting cradle 905 downward, thereby separating the wafer 902 from the susceptor 903. Then, after the wafer transfer arm 911 is inserted between the wafer 902 and the susceptor 903, moving means for moving both the susceptor supporting cradle 905 and the wafer supporting cradle 909 downward is required.
Further, in order to enhance the uniformity in thickness of a thin film formed onto the wafer, the prior art also includes rotating means for rotating the susceptor 903. Therefore, complicated vertically moving/rotating means 912 comprising means for vertically moving the two cradles 905 and 909 and rotating means for the susceptor 903 which are coaxially incorporated is required at a lower portion of the reaction chamber.
Further, in order to decompress the reaction chamber, it is necessary to dispose a plurality of O-rings for vacuum sealing in the vertically moving/rotating means 912. Therefore, the above-described prior art has a problem that the vertically moving/rotating means 912 having extremely complicated structure is required.
Further, Japanese Patent Application Laid-open No. H8-97274 discloses a wafer thermal treating apparatus comprising first and second transfer means in its reaction chamber. However, when such transfer means are provided in the reaction chamber, dust and the like can not be prevented from being generated from mechanically sliding portions, and it is not preferable because this can be a factor of contamination of a semiconductor wafer.